# #45 drill size

A #45 drill is 0.0820 in (2.08 mm). It is the standard tap drill for #3-56 UNF; the nearest metric drill is 2.1 mm.

## #45 drill data

- Series: Number drill
- Decimal: 0.0820 in
- Metric: 2.08 mm (2.0828 mm exact)
- Nearest metric drill: 2.1 mm (+0.017 mm)
- Nearest fractional: 5/64" (0.0781 in)
- Standard tap drill for: #3-56 UNF

## Nearest metric drills

| Metric drill | Inch | Difference |
|---|---|---|
| 2.05 mm | 0.0807 | −0.033 mm |
| 2.1 mm | 0.0827 | +0.017 mm |

## Nearby inch drills

| Drill | Series | Inch | mm |
|---|---|---|---|
| 5/64" | Fractional | 0.0781 | 1.98 |
| #46 | Number | 0.0810 | 2.06 |
| #45 | Number | 0.0820 | 2.08 |
| #44 | Number | 0.0860 | 2.18 |
| 3/32" | Fractional | 0.0938 | 2.38 |
| Letter A | Letter | 0.2340 | 5.94 |

## Threads this drill can tap

| Thread | Standard drill | Thread % with this drill |
|---|---|---|
| #3-56 UNF | #45 | 73 |
| M2.5 × 0.45 | 2.05 mm | 71 |
| #3-48 UNC | #47 | 63 |

## Clearance

| Fastener | Diameter | Clearance | Per side | ISO 273 |
|---|---|---|---|---|
| #1 screw | 0.0730" | 0.0090" | 0.0045" | – |
| M2 bolt | 2 mm | 0.08 mm | 0.04 mm | Tighter than close fit (2.2 mm) |


## FAQ

**What size is a #45 drill?**
A #45 drill is 0.0820 in, which is 2.08 mm (2.0828 mm exactly).

**What is the metric equivalent of a #45 drill?**
The nearest metric drill is 2.1 mm, 0.017 mm larger. The other close size is 2.05 mm.

**What tap uses a #45 drill?**
A #45 drill is the standard tap drill for #3-56 UNF (about 73 % thread).

**Which fractional drill is closest to #45?**
5/64 in (0.0781 in) is the closest, 0.0039 in smaller.

**What does a #45 drill clear?**
It clears a M2 bolt with 0.08 mm total clearance (0.04 mm per side); for metric bolts: tighter than close fit.

Source page: https://machinistcharts.com/drill-size/number-45/
Updated: 2026-10-06
Publisher: MachinistCharts (https://machinistcharts.com)